Manganese nickel alloy



a corporation of Illinois PATENT OFFICE 2,339,252 MANGANESE NICKEL ALLOY Reginald S. Dean, Washington, D. 0., and Clarence T. Anderson, Pittsburgh, Pa., assignors to Chicago Development Company, Chicago, 111.,

No Drawing. Application November 6, 1939,

Serial No. 303,007

,2 claims. (01. 148-32) This invention relates to alloys of manganese and nickel. It relates to ductile alloys of man aged at 550 degrees C.

?% Hardness, Rockwell c Rapidly Cold Aged at Aged at Mn cooled worked 450 0. 550 C.

no 40 -4 +20 +52 an 65 36 --4 21 4s 25 70 so -11 1s 21 s 75 2a -12 14 14 a so 20 -20 1o 10 5 s5 15 -21 o o 20 90 1o -22 5 a as This table shows that alloys containing less than 70% manganese harden greatly when aged at 450 degrees C. after quenching. Alloys from 70% to 80% manganese show relatively little hardening at 450 degrees C. Alloys containing more than 80% manganese show no hardening at 450 degrees C., but harden at 550 degrees C.

The table illustrates results obtaining by aging after quenching and cold working. Similar results may be obtained by eliminating the cold working step, it being understood, of course, that the rates of hardening ar somewhat aflected by the cold working. These alloys are non-magnetic. Their electrical resistance is relatively high in the quenched state. Alloys containing less than approximately 70% manganese show a decrease electrical resistance on aging, while alloys containing more than 80% manganese show an increase of electrical resistance on aging. This is illustrated by the following table:

0 posl- Emmi mmxma n ohms/an.

quenched AM Aged M Ni and cold.

assesses assesses We have found that the temperature coeflicient of these alloys passes through zero between 65 and 70% manganese. With more manganese than 70%, the temperature coefficient is positive, while with less manganese, the temperature coeiiicient is negative. The coeiiicient of expansion of these alloys passes through a maximum at approximately '70% manganese having a value of more than 22.5X 10- cm./ cm./ deg. C. From this maximum it falls to approximately 16x 10- cmF/deg. C. at 50%, and to 15x10- cmfi/deg. C. at 90%.

The alloys containing more than 70% manganese may be obtained with high vibration damping capacity by suitable heat treatment. We have found that a suitable heat treatment is to quench from 900 degrees C. and age at 450 degrees C. Under these conditions, vibration damping capacity of greater than 2% can be obtained. This figure may be compared to a corresponding figure for certain steels which is less than .04%.

,The tensile strength in the quenched, and cold worked alloys follows the Rockwell hardness in a manner approximately similar to steel. The quenched and cold worked alloys are especially tough in the quenched condition. The elongation in this condition is more than 40% in two inches, with tensile strengths as high as 75,000 lbs. per sq. Alloys within the range given, containing less than manganese, are tough in the aged and hardened states. Extreme hardness in-alloys containing more than 70% manganese is accompanied by some brittleness, but

not enough to prevent their being employed for many useful purposes.

What is claimed as new and desired to be protected by Letters Patent of the United States is:

1. A ductile alloy of manganese and nickel containing from to manganese, hardened by quenching from a temperature between 800 degrees C. and'its melting point and aging at a temperature above500 degrees C.

2. A ductile alloy of manganese and nickel containing from 75% to 95% of electrolytic man ganese of high purity, said alloy being hardened by a heating, quenc aging procedure.

REGINALD S. DEAN. CLARENCE T. ANDERSON. 

